Patent GB-618017-A (GB)
Title: Improvements in sliding anti-friction bearing
Inventor: JOHN BURRY THOMSON
IPC: F16C29/06
Filed: 1946-10-14
Abstract: 618,017. Rectilinear - motion bearings. THOMSON, J. B. Oct. 14, 1946, No. 30599. Convention date, Nov. 6, 1945. [Class 12 (i)] A rectilinear-motion ball bearing for a shaft, wherein the balls are held between the shaft and a sleeve by a retainer providing one or more endless ball-raceway circuits having straight axially-directed portions and curved end portions, is characterised in that the inner face of the sleeve is counterbored at each end, the curved portions of the circuits lying within the areas defined by the counterbores, and has longitudinal recesses extending from one counterbore to the other, which recesses register with alternate straight portions of the circuits, so that the balls as they traverse the curved portions of the circuits and the said alternate straight portions will be relieved of the load. A cylindrical sleeve 10, Fig. 3, is counterbored at each end 12 within the areas denoted by the broken lines a-b, c-d, and has three longitudinal recesses of the same depth as the counterbores and extending from one counterbore to the other. Inserted between the sleeve 10 and shaft 11 are ball-retaining and guiding members 14, 15 comprising end caps 17 which abut against the ends of the sleeve and from each of which long fingers 16 project alternately, forming with the shaft 11 one continuous closed ball circuit consisting of a number of ballguides 18, 19 and, within the area defined by the counterbores, a number of approximately semicircular guides 20. If the end caps 17 are keyed to the sleeve 10 so that the guides 19 register with the recesses in the sleeve, the depths of the guides 19, 20 will be equal, the recesses being of the same depth as the counterbores, and will be greater than the depth of the guides 18, i.e. the radial distance between the shaft and those parts of the sleeve 10 which lie between the counterbores and are not recessed; consequently, since the diameter of the balls is such that balls in the guides 18 bear upon both the shaft and the sleeve, balls in the return guides 19 and connecting guides 20 will be free to go where impelled by movement of the balls in the guides 18. Thus, as the bearing travels along the shaft, the balls will move continuously round the circuit, balls discharged from the guides 18 into the connecting guides 20 being released from bearing contact with the shaft and sleeve and delivered into the return guides 19. The recesses in the sleeve 10 may be approximately equal either to the diameter of the balls, Fig. 4 (not shown), or to the diameter of the balls plus twice the width of one of the fingers 16, Fig. 8 (not shown). In a modification, Fig. 9, the ballretaining and guiding means comprise an auxiliary sleeve 25 which fits closely in the outer sleeve and has oval parts 26 cut out. The edges of the parts 26 and of the openings left in the sleeve are then bevelled, so that when the parts 26 are replaced in said openings oval slots for the balls are formed, providing longitudinal guides 18<SP>1</SP>, 191 and semicircular guides 20<SP>1</SP>. After the slots have been filled with balls, the sleeve 25 is slid into the outer sleeve and secured thereto, by screws which go through the outer sleeve and are threaded into the parts 26, in such a position that the guides 19<SP>1</SP> register with the recesses in the outer sleeve. Movement of the balls is as in the first construction.